This application constitutes an improvement of an impact actuated reciprocating mower of the type disclosed in my prior U.S. Pat. Nos. 3,657,868 and 3,802,171. In these prior patents, a rotary impactor was employed to linearly reciprocate two elongated cutting bars relative to each other, each bar carrying a plurality of cutting teeth. A spring was utilized to return the cutting bars to an open or aligned position of the cutting teeth in between the successive impacts.
Experimentation with these constructions revealed the fact that the cutting action of the blades was not as consistent or as powerful as desired, and it was determined that this was primarily due to the inertia effects of the relatively large mass of the elongated blades, coupled with the fact that the impact forces were always operating against the returning force of the spring.
Additionally, the elongated cutting bars were expensive to manufacture, difficult to sharpen, and required precise alignment when assembled on the mower.
In recent years, the Black & Decker Company, of Towson, Maryland, has marketed a hand-held trimming device for grass or hedges wherein the cutting blade assembly comprises two forklike members which are disposed in overlying relationship and mutually riveted together. The one forklike member is fixed to the frame of the device, while the other member is rapidly pivotally reciprocated relative to the fixed forklike member to provide a scissorlike cutting action between the tines of the forklike members, which have sharpened edges which cooperate with each other to effect the cutting action. These forklike members are inexpensively manufactured from stampings and are purchasable as completely assembled units at a price which is so reasonable as to cause the average householder to throw away any unit that has become dull or damaged and replace it with a new factory-assembled unit. The desirability of utilizing these types of cutting elements in a full-size lawn mower is readily apparent.